-LRB- CNN -RRB- -- There is a phrase that has long been used in discussing nuclear warfare :

Mutual assured destruction .

What it means is that if various enemies develop and use the most powerful and harmful weapons available , everyone will lose . Everyone will die .

National politics is not literal warfare , although its practitioners like to use the language of combat :

War rooms .

Battleground states .

Attack ads .

And as the political world shifts its focus from one national convention to the other , a sentiment has been building that this year 's presidential campaign may turn out to be the dirtiest ever .

You 've already seen it in the wall-to-wall television commercials during the primary season ; with the fall campaign shifting into overdrive , you can expect the tone of the advertising to make sewage seem pristine by comparison . As Peggy Noonan wrote in The Wall Street Journal : `` With all the PAC money floating around , we 've entered the Golden Age of mudslinging . ''

It 's not that the candidates are incapable of high-mindedness ; they are extraordinarily bright . But in recent years the mantra of high-octane campaigns has been that below-the-belt tactics work , and the rationalization has been that a candidate ca n't accomplish anything worthy if he or she does n't get elected in the first place .

Jim Rutenberg , in The New York Times , under the headline `` The Lowest Common Denominator and the 2012 Race for President , '' wrote last month : `` The thinking was that the two presidential candidates , both with Harvard degrees , would finally use their intellectual prowess to discuss the nation 's challenges seriously . '' That , he wrote , is looking like an unrealistic expectation , and thus `` Strategists on both sides are pondering which campaign is best served by the vitriol . ''

From time to time there are public calls for a truce in the invective . It never seems to stick . Carol E. Lee , writing in The Wall Street Journal : `` Neither side shows any signs of curtailing the negativity . ... One effect of such early negativity is that both candidates figure to be battered by November , and voters could become fatigued earlier . ''

Why does this matter ? With politics more of a spectator sport than ever , what is the real harm in its devolving into an only slightly more refined version of mud wrestling ?

The harm is that it 's a difficult shift to go from mud wrestler to statesman once the votes are counted . The metaphorical eye-gouging and groin-kicking of take-no-prisoners campaigns may be effective in grabbing voters ' attention -- increasingly , watching a presidential campaign play out is like slowing down to gape at a particularly ugly auto accident . But there are indications that the voters are getting wise to the game , and becoming disillusioned with it .

In a front-page story in USA Today before the conventions began , Susan Page reported that a USA Today/Gallup Poll `` finds Americans taking a decidedly more negative view of the presidential candidates and the tenor of their campaigns than they did four years ago . ''

Some of the findings of the poll : Voters are critical of both candidates for making unfair attacks on each other . To an extent not seen in at least the last six election seasons , voters say that they view both the Republican and Democratic parties unfavorably . When , in 2008 , potential voters were asked if both candidates would make good presidents , 25 % said yes . This year , asked the same question , only 12 % said yes .

And that is the danger of mutual assured destruction , politics-style . In warfare , the hoped-for impact of the knowledge that either side could annihilate the other was to preserve a state of peace , however strained or uneasy -- it was , and is , a doctrine of deterrence . In politics , it does n't seem to inhibit the combatants .

A willingness to use any means to win an election will inevitably , in the end , produce a president . But then the president will have to lead a nation that has turned darkly cynical about the entire process .

There is a publication that has none of the glitz or dinner-party cachet of the national newspapers or television news networks , but it reaches an audience that dwarfs theirs . The publication is the AARP Bulletin -- circulation 22 million -- and its editor , Jim Toedtman , recently wrote an editorial that puts all of this in measured perspective .

Under the headline `` Leaders , Try Greatness , Not Meanness , '' Toedtman said that strategists for the opposing sides are displaying `` no interest in compromise , '' and quoted Allegheny College President James H. Mullen Jr. in characterizing the current process as `` a disgraceful stew of invective ... a continuing contest in which each side of the partisan divide sees itself as right and the other as evil , uncaring or , worst of all , unpatriotic . ''

Does it have to be this way ? The editorial recalls John Adams , who `` could just as easily have been talking about today when he wrote in 1776 of his fears that the Continental Congress ' decisions would be dictated ` by noise , not sense ; by meanness , not greatness ; by ignorance , not learning ; by contracted hearts , not large souls . ' ''

Adams wrote , `` There must be decency and respect and veneration introduced for persons of authority of every rank or we are undone . In popular government , this is our only way . ' ''

When the country loses that , it loses something essential . Just what is it that we are throwing away ? Toedtman 's editorial concludes : `` Decency , respect and veneration produced compromise and a foundation that has endured for 236 years . We are surrounded by noise , meanness and ignorance . The measure for our leaders must be their ability to rediscover that proven formula of sense , greatness and learning . ''

But what political consultant would waste his client 's money trying to fit those sentiments into a 30-second commercial ?

Meanwhile , Election Day is less than 10 weeks away .

The opinions expressed in this commentary are solely those of Bob Greene .

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Bob Greene : Political campaigns resemble warfare 's mutually assured destruction

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He says politicians believe the only way to win is by using below-the-belt tactics

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A poll showed that Americans take an increasingly dim view of negative campaigns , candidates

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Greene : When the country loses decency , respect , it loses something essential